Does Blast Medium Affect Heterotopic Ossification in a Blast-amputation Model?

Abstract

Background Heterotopic ossification (HO) develops after nearly 2 .3 of traumatic blast amputations in the contemporary battlefield. This phenomenon has potentially devastating consequences for servicemen and women and its pathophysiology warrants further investigation using a previously developed animal blast model. Questions/purposesWe asked, what is the (1) severity (quantity) and (2) type (location) of HO bone formation after a hindlimb blast amputation with two distinct blast media. We hypothesized that a more ''war-relevant'' blast medium could be a more accurate model and potentially intensify the development of HO. Methods Using a Sprague-Dawley rat model, the pathophysiology of ectopic bone formation in a traumatic hindlimb blast amputation was evaluated. Twenty-four animals underwent blast amputations and closure based on a previously established experimental model. Half the amputations were subjected to blasted sand and the other 1/2 to blasted water. Serial orthogonal radiography was performed on each animal until euthanasia at 24 weeks to track the development of HO. Heterotopic bone severity and type were assessed by three independent graders at each time using a novel grading scale to assess quantity and quality of HO. Results All animals had radiographic evidence of HO develop. No differences were observed in ectopic bone development between sand and water blasting regarding severity or type at any time. Animals that received water and sand blasting had moderate HO develop at 24 weeks (median, 2.0 and 2.5 weeks, respectively; range, 1-3 weeks; difference of medians, 0.5; p = 0.67). At the time of euthanasia, 10 animals that were water blasted had Type 3 HO compared with 11 in the sand-blasted group (p = 1.00).The institution of one or more of the authors (DEJ, VDP) has received, during the study period, funding from the United States Department of Defense Congressionally Directed Medical Research Program (Washington, DC, USA). One of the authors certifies that he (VDP), or a member of his immediate family, has or may receive payments or benefits, during the study period, an amount of USD 100,000-USD 1,000,000, from the United States Department of Defense Congressionally Directed Medical Research Program (Washington, DC, USA), an amount of USD 100,000-USD 1,000,000 from DePuy Orthopaedics (Warsaw, IN, USA), and USD 100,000-USD 1,000,000 from the Agency for Healthcare Research and Quality (Rockville, MD, USA). Conclusions Our study showed a clear development of HO after hindlimb blast amputation in a Sprague-Dawley rat model; however, no difference was observed in HO development based on the type of blast media. This suggests it is the blast mechanism that induces ectopic bone development, regardless of the blasted medium. The grading scale we developed for our animal-model study provided a reliable means of assessing HO severity and type. Clinical Relevance We anticipate that future investigations will elucidate similarities between service members' wartime extremity injuries and the animal...

The traumatic bone: trauma-induced heterotopic ossification

“…Tannous et al 52 utilized this method in a rat model, to demonstrate that hindlimb amputation leads to significantly higher rates of HO than forelimb amputation. Utilizing the same procedure, Jaffe et al 53 reported that the type of blast media (sand vs water) has no difference on the development or the severity of HO.…”

The development of a mouse model to investigate the formation of heterotopic ossification

“…The researchers from Pellegrini’s lab established the HO rat model following blast Am procedure, and found that HO demonstrated early fibroproliferative signature. 17,18 In addition, the study from Forsberg and Potter’s lab confirmed that the serum from HO patients could activate mitogen activated protein kinase signaling in adipose stem cells. 19 The authors from Levi and Davis’s Lab found that BMP signaling made great contribution to osteogenic differentiation as well as ectopic bone formation and blocking BMP signaling may be an effective prophylactic strategy for HO following blast-related lower extremity trauma.…”

“…The animal study protocol was approved by Animal Care and Use Committee of our institution (Protocol No. 18,032,493). A total of 42 mice (8-10 weeks old, male C57BL/6J mice), purchased from Jackson laboratory, were randomly divided into three groups: Am group (Am of right hindlimb, n = 12), CTX group (CTX injection in the calf muscle of left hindlimb, n = 12) and Am + CTX group (the combination of Am and CTX injection, first Am of right hindlimb, subsequently CTX injection in the calf muscle of left hindlimb, n = 18).…”

Development of a rodent high-energy blast injury model for investigating conditions associated with traumatic amputations

“…Prior work has developed various rat models in which a shock tube is used to investigate the impact of different magnitudes and duration of the blast pressure in inducing inflammation. 29 Others used a pentaerythritol tetranitrate explosive, submerged beneath a water tank 30 or sand container 31 to induce the fracture. The majority of these models used blast and a separate drop weight to create the fracture.…”